Noemí Palma1, Maria J Pons2, Cláudia Gomes1, Judit Mateu1, Maribel Riveros3, Wilfredo García3, Jan Jacobs4, Coralith García3, Theresa J Ochoa5, Joaquim Ruiz6. 1. ISGlobal, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain. 2. Universidad Peruana de Ciencias Aplicadas, Lima, Peru. 3. Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru. 4. Institute of Tropical Medicine, Antwerp, Belgium; Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium. 5. Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru; Center for Infectious Diseases, University of Texas School of Public Health, Houston, TX, USA. 6. ISGlobal, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain. Electronic address: joruiz.trabajo@gmail.com.
Abstract
OBJECTIVES: To characterise the β-lactam, quinolone and macrolide resistance levels and mechanisms in 62 Escherichia coli isolates causing bacteraemia in Peruvian children. METHODS: Minimum inhibitory concentrations (MICs) of ciprofloxacin, nalidixic acid (NAL) and azithromycin were determined in the presence and absence of Phe-Arg-β-naphthylamide. Susceptibility to other 14 antimicrobial agents was also established. Extended-spectrum β-lactamases (ESBLs) were identified, and mutations in gyrA and parC as well as the presence of transferable mechanisms of quinolone resistance (TMQR) and macrolide resistance (TMMR) were determined. RESULTS: Fifty isolates (80.6%) were multidrug-resistant. High proportions of resistance to ampicillin (93.5%), NAL (66.1%) and trimethoprim/sulfamethoxazole (66.1%) were observed. No isolate showed resistance to carbapenems and only two isolates were resistant to nitrofurantoin. Twenty-seven isolates carried ESBL-encoding genes: 2 blaSHV-12; 13 blaCTX-M-15; 4 blaCTX-M-2; 6 blaCTX-M-65; and 2 non-identified ESBLs. Additionally, 27 blaTEM-1 and 9 blaOXA-1-like genes were detected. All quinolone-resistant isolates showed target mutations, whilst TMQR were present in four isolates. Efflux pumps played a role in constitutive NAL resistance. The association between quinolone resistance and ESBL production was significant (P=0.0011). The mph(A) gene was the most frequent TMMR (16 isolates); msr(A) and erm(B) genes were also detected. Only one TMMR-carrying isolate [presenting mph(A) and erm(B) concomitantly] remained resistant to azithromycin when efflux pumps were inhibited. CONCLUSIONS: A variety of ESBL-encoding genes and widespread of blaCTX-M-15 in Lima has been shown. The role of efflux pumps in azithromycin resistance needs to be further evaluated, as well as effective control of the use of antimicrobial agents.
OBJECTIVES: To characterise the β-lactam, quinolone and macrolide resistance levels and mechanisms in 62 Escherichia coli isolates causing bacteraemia in Peruvian children. METHODS: Minimum inhibitory concentrations (MICs) of ciprofloxacin, nalidixic acid (NAL) and azithromycin were determined in the presence and absence of Phe-Arg-β-naphthylamide. Susceptibility to other 14 antimicrobial agents was also established. Extended-spectrum β-lactamases (ESBLs) were identified, and mutations in gyrA and parC as well as the presence of transferable mechanisms of quinolone resistance (TMQR) and macrolide resistance (TMMR) were determined. RESULTS: Fifty isolates (80.6%) were multidrug-resistant. High proportions of resistance to ampicillin (93.5%), NAL (66.1%) and trimethoprim/sulfamethoxazole (66.1%) were observed. No isolate showed resistance to carbapenems and only two isolates were resistant to nitrofurantoin. Twenty-seven isolates carried ESBL-encoding genes: 2 blaSHV-12; 13 blaCTX-M-15; 4 blaCTX-M-2; 6 blaCTX-M-65; and 2 non-identified ESBLs. Additionally, 27 blaTEM-1 and 9 blaOXA-1-like genes were detected. All quinolone-resistant isolates showed target mutations, whilst TMQR were present in four isolates. Efflux pumps played a role in constitutive NAL resistance. The association between quinolone resistance and ESBL production was significant (P=0.0011). The mph(A) gene was the most frequent TMMR (16 isolates); msr(A) and erm(B) genes were also detected. Only one TMMR-carrying isolate [presenting mph(A) and erm(B) concomitantly] remained resistant to azithromycin when efflux pumps were inhibited. CONCLUSIONS: A variety of ESBL-encoding genes and widespread of blaCTX-M-15 in Lima has been shown. The role of efflux pumps in azithromycin resistance needs to be further evaluated, as well as effective control of the use of antimicrobial agents.
Authors: Vuong Van Hung Le; Ieuan G Davies; Christina D Moon; David Wheeler; Patrick J Biggs; Jasna Rakonjac Journal: Antimicrob Agents Chemother Date: 2019-10-22 Impact factor: 5.191